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Old 06-05-2003, 01:14 PM   #1
cmeseadoin
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1994 Ford Taurus SHO CHECK ENGINE LIGHT

Greetings, It's me again!
I have a 1994 Ford Taurus SHO with the 3.2L engine and automatic transmission. The car has 79K miles on it. This is my father's car and it has had the CHECK ENGINE light on for the longest time. The light does not come on and stay on from the time you start the engine, but within 10 miles or so it comes on and does not flash, it stays illuminated until the engine is turned off and then re-fired. Then the process begins again. When the problem started occurring a while back, the light was flashing several times and would go on and come off intermittently. He has taken it to the shop, the ignition module was replaced due to other problems and also two of the o2 sensors were detected to be bad. I did not have a scanner back when this first occurred so it went to the shop. This car is a nice vehicle but FORD has plaqued it with electrical/computer issues that most often involve the CHECK ENGINE light because it is very very complex electrically. He has spent lots of money on the car and when the light started coming on again he basically just let it go because the car experiences no drivability problems or anything at all and he is basically sick of spending money only to see that light re-illuminate which I can't blame him. I recently purchased an EZ SCAN 6000 OBD I-II scanner that will read all computers from 83 up till now including OBD I and II. The last time he took it in to have the CHECK ENGINE light accessed but not repaired, the shop told him that the EGR valve was deffective and needed replacing and that was the reason the light was on. When I scanned it myself the other day there were two OBD I memory codes in the computer. The first was code 124: Throttle Position Sensor Higher than expected and also a code 332: EGR flow insufficient. I have done some research and have a few friends with FORDs. I know that the DPFE sensor AKA EGR valve position sensor is a trouble prone sensor on these cars with this milage. I know that this sensor measures differentials in pressure across the restriction in the EGR system to report the status of the EGR valve position to the PCM. At idle the voltage of this sensor is typically at 0.6V and at this voltage the EGR valve should NOT be open because no EGR activity should be taking place at idle. As the engine speed increased along with other sensor data the voltage to/from this sensor to the PCM increases and that tells the EGR vacuum solenoid to increase in % opening to let more exhaust gases into the intake. SO, I scanned the computer yesterday and then took a look at the sensor data while the engine was at idle. My EGR FEEDBACK (DPFE VOLTAGE) was at 0.5V to start with and the EGR VACUUM SOLENOID was at 0.0%. That is one tenth of a volt lower than it should be. My first intuition is that this sensor is reporting falsly to the PCM at idle and that might be to problem. KEEP IN MIND, the code 332 is for INSUFFICIENT EGR FLOW, not EXCESSIVE. I decided to drive the vehicle and watch the data. As I accelerated the voltage was around .5-.6V and the egr solenoid reported 0.0% opening. As I cruised without acceleration, the voltage on the DPFE never got above .9V and the egr vacuum solenoid never reached more than 54% and usually was around 24%. To me that is insufficient. The CHECK ENGINE light came on again. Same code. My assumption: The voltage that the DPFE sensor is reporting to the PCM is too low at the optimal time, therefore, the EGR VACUUM SOLENOID is never opening like it should. This is causing the 332 EGR FLOW INSUFFICIENT error code. The engine NEVER stumbles at idle, misses on acceleration or anything. That tells me the EGR valve is not malfuntioning. I don't have a vacuum tester, but my guess would be that if I actuated the valve by tester at idle, the engine would start to stumble and then return to normal after removing the vacuum. I then took off the DPFE and drilled the rivets and pulled that bad boy apart. I cleaned it well and cleaned the connections on the computer printed circuit and then put it back together with small nuts and bolts inplace of the rivets. Now when she idles it is at around 0.6V everytime but when driven, it never exceeds 0.9V still and the EGR VACUUM SOLENOID never reaches more than 54% with 24% still being about average. I think that voltage should go on up to around 2.07V and that would open the solenoid for the EGR more. I think I found the problem, What do you think? As far as the TPS sensor error, I am not quite sure yet about that, maybe that is bad too, MORE MONEY! Thanks!
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Old 06-05-2003, 01:43 PM   #2
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Once again you've done an excellent job of describing and troubleshooting. Replace the DPFE sensor. I have seen this several times and it takes care of both codes. No I haven't figured out exactly why yet.
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Old 06-05-2003, 02:35 PM   #3
cmeseadoin
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Thanks again!

You know, the ONLY other thing I should do first is get a vacuum tester and test to make sure that the EGR valve when actuated at idle makes the engine start to stumble. I was just reading a case file where someone had the EXACT same problem on a 1991 FORD TAURUS 3.0L 6 cyl with 141K on it. They tested the egr with vacuum and with 10 inches of vacuum applied the valve opened fully but there was NO affect on engine performance at idle. The EGR port in the intake ended up being blocked and it was not the valve nor the DPFE. They were getting the 332 EGR flow insufficient code as well. That damn DPFE is anywhere from 70-150 dollars depending on who you call. What do you think about that? Probably more of a chance that the DPFE is bad because FORD has a problem with those particularly around this mileage, but I was thinking of checking all ports tonight as well as vacuum testing the EGR valve to make certain it is working and that all ports are open and free before ordering that sensor. Should it be possible to blow in either the REF or HI inlet port on the DPFE and have the air exit from the opposite side? I have not tried that but I have applied suction to either side and there is 100% restriction. You can't do it. Please let me know what you think, thanks again! :-)
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Old 06-05-2003, 04:00 PM   #4
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Yes you're absolutely correct. I misread what you said in the first post (old age is hell). I thought you said you HAD tested the EGR valve with a vacuum tester. Do that before spending the money on the DPFE. Hope you haven't spent the money yet.
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Old 06-05-2003, 04:25 PM   #5
cmeseadoin
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DPFE

No, I haven't. I am going to test that tommorrow, some plans developed for this evening. I will test the EGR and then make sure that all ports are open and that the EGR valve is working. Should DPFE allow passthrough or should there be no allowance for suction or blowthrough when testing it? Thanks again!
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Old 06-05-2003, 06:41 PM   #6
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Re: DPFE

Quote:
Originally Posted by cmeseadoin
No, I haven't. I am going to test that tommorrow, some plans developed for this evening. I will test the EGR and then make sure that all ports are open and that the EGR valve is working. Should DPFE allow passthrough or should there be no allowance for suction or blowthrough when testing it? Thanks again!

Negative on the blowthrough. If I remember correctly it has a thick film diaphram. If you apply to much vacuum you can cause permanent damage. Keep it to no more than 50% above what you would see in the intake on over run.
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Thanks for the pic, jedimario.

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Old 06-05-2003, 06:58 PM   #7
cmeseadoin
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blowthrough

Ok thanks VWHOBO, I am going to check that out first before getting that sensor. I found a place five minutes from me that can get the DPFE by tommorrow for me, no payment to order req'd, so I did that incase my test tonight/in the morning reveals I need it, then I can get it. 79.25, cheapest around and it made for that car. I will let you know. Thanks
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Old 06-05-2003, 07:14 PM   #8
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Re: blowthrough

Quote:
Originally Posted by cmeseadoin
Ok thanks VWHOBO, I am going to check that out first before getting that sensor. I found a place five minutes from me that can get the DPFE by tommorrow for me, no payment to order req'd, so I did that incase my test tonight/in the morning reveals I need it, then I can get it. 79.25, cheapest around and it made for that car. I will let you know. Thanks

Just make sure it's good quality, not Wells (Autozone) or GP Sorenson (Advance). Would you believe my price for a Standard is under $50?
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Thanks for the pic, jedimario.

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Old 06-05-2003, 08:12 PM   #9
cmeseadoin
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DPFE

Hey thanks, the one I am looking at is from CarQuest. I have done business with them a few times and everything seems fine. Aftermarket parts are a 50-50 shot sometimes , but hey, the dealer wants 119.00 and another wants 150.00. They can kiss my white ass, LOL.
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Old 06-09-2003, 01:22 PM   #10
cmeseadoin
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Check Engine Light

Ok, this car has completely pissed me off now. On Friday I ran some more tests on the EGR system on the SHO before I decided that it was absolutely positively the DPFE sensor. I tested the Vaccum lines running from the ports on the Vacuum Solenoid that takes the ported intake vacuum from the intake and proportions it back to the egr valve itself. Both the supply line and the return line were fine and held a tight vacuum. I then took off the EGR valve and checked it and everything was fine. It operates correctly with vacuum applied and was not gunked up. Keep in mind that the error I am receving is a code 332, EGR flow insufficient (not excessive). I am thinking that this is being set while driving because that is when the light comes on, not at idle as there should be no EGR flow at idle. I figured, ok, I've done all the testing that I can do to this thing and it must be the DPFE. I went and got one for 76 bucks and installed it. It was holding 0.6V at idle as it should and then it would increase to around 1.0V while driving and that was the highest voltage that seemed to occur under any driving condition. I drove the car on a test drive with all codes cleared and had the scanner hooked up monitoring EGR feedback voltage and solenoid %. I set cruise on the interstate to 73MPH and noticed that EGR solenoid % held steady at 24.7% which seems low to me. Sure as shit the CHECK ENGINE light comes back on. What's the code?, SAME 332 again! WHAT is going on? I dont have a bad EGR valve as every test indicates it's working, the vacuum lines are fine and there is no carbon buildup anywhere. The DFPE is now NEW and the only other thing I can think of is that the Vacuum solenoid valve is bad. It's just a little canister that is attached to the back of the firwall with an electrical connection and two vacuum lines. If that is not working correctly then the EGR wont apply the vacuum needed to the EGR valve. I have taken the DPFE out and replaced it with the old one because I think the old one is fine. The voltage feedback and solenoid % are the same values as with the new one under the same driving conditions. The auto parts place took it back as I told them I bought it and did not need it. Shit, it was 76 bucks, oh well, call me bad for doing that. So now I have the old DPFE back in there and the ONLY thing I can think of now is the vacuum supply solenoid. What I don't understand and help me out here.......everytime I perform a KOER (key on engine running) test to the car, the only code that comes back everytime is 332 EGR flow insufficient. WHY am I getting an insufficient flow code at idle with KOER when there should be NO flow at idle???? I am decidedly getting lost with this problem. Thanks for any help. Should I pick up a vacuum solenoid for 32 bucks at the local ford dealership where I've priced it and try that? Thanks!!
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Old 06-09-2003, 01:26 PM   #11
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sidenote

Oh, and now after screwing around with the new DPFE and pulling the EGR valve off to clean and inspect it and then reinstalling the old DPFE, when the check engine light comes on, it comes on and then will go off again within a few minutes. Then it will come on and go off in this on/off cycle. It used to stay on once it came on until the engine was turned off and re-cranked. WTF?
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Old 07-09-2003, 03:57 AM   #12
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Ok, I'mnot an expert, but I'll try. You said that you cleared the codes and it came back. Did you try disconnecting the negative battery cable and reconnecting it after about five minutes? In my experiences, this always cleared the code(s) and that was that. It could very well be an intermitten problem. If it comes on and off repeatedly, it could be a minor malfunction of the PCM or there could be a short somewhere after you've tampered with it. I don't know for sure, but that's my opinion. I hope it all works out for you and that you get it fixed!
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Old 07-09-2003, 01:16 PM   #13
cmeseadoin
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check engine light

Hey Ferrarichika,

Thanks for the information, believe you me, I have troubleshot this thing from every direction. If it were as simple as a battery disconnect, then I would have had it nailed about 3 months ago, LOL. All that does is to possibly clear any temporary fault codes and allow the computer to reset itself. I use the actual computer scanner for the car which is far better than disconnecting the battery because it goes in and talks to the computer to clear the codes using the protocol of which the computer connects. I found the problem, the vacuum solenoid is bad and is not regulating the vacuum from the intake to the egr valve itself correctly. A 32$ part from FORD. Thanks for the efforts though, :-) take care
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Old 07-09-2003, 05:35 PM   #14
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Quote:
Originally Posted by ferrarichika
Ok, I'mnot an expert, but I'll try. You said that you cleared the codes and it came back. Did you try disconnecting the negative battery cable and reconnecting it after about five minutes? In my experiences, this always cleared the code(s) and that was that. It could very well be an intermitten problem. If it comes on and off repeatedly, it could be a minor malfunction of the PCM or there could be a short somewhere after you've tampered with it. I don't know for sure, but that's my opinion. I hope it all works out for you and that you get it fixed!

You should have stopped after the second comma!

It's people like you that do this backyard bullshit with their car and THEN take it to a shop that makes a professionals life hell. At best you'll kill the MIL for a short while. At worst you'll ruin any chance for us to use the PCM and scan tool as intended and maybe catch a freeze frame, espesially if it's an intermittent.

Moral of the story is unless you WILL complete all diagnosis and repair on your own, don't touch it..
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